Change array values based on a reference array

Question

I have a PHP variable like:

$genre = 'crime / thriller / mystery / adventure';

I use the following piece of code to convert it to an array of genres:

$return['movie_genre'] = array_map('trim', explode('/', $genre));

I also have another reference array, like:

$references = array(
    'crime' => 9896,
    'biography' => 9898,
    'western' => 9899,
    'drama' => 9901,
    'action' => 9902,
    'news' => 9903,
    'sci-fi' => 9904,
    'thriller' => 9906,
    'history' => 9907,
    'animation' => 9909,
    'comedy' => 9910,
    'musical' => 9911,
    'music' => 9912,
    'mystery' => 9913,
    'documentary' => 9914,
    'family' => 9915,
    'adventure' => 9916,
    'war' => 9917,
    'reality-tv' => 9919,
    'romance' => 9920,
    'sport' => 9921,
    'game-show' => 9922,
    'talk-show' => 9923,
    'horror' => 9924,
    'fantasy' => 9925,
    'film-noir' => 9926,
);

, where I'd like to lookup the textual values of the first array, and replace them with their numerical references of the reference array, ending up to something like this (for the above example):

[movie_genre] => Array
    (
        [0] => 9896
        [1] => 9906
        [2] => 9913
        [3] => 9916
    )

Let me be clear, I'm not looking for a foreach solution. That one, I can write myself. I'm looking for an elegant one-liner, like another array_map, or array_walk; ideally if I could combine it with the one-liner I already use to create the array itself from the initial string variable. But I can't thing of anything elegant... Any help would be much appreciated. TIA.

Some people value performance and maintainability over clever one-liners. ¯\_(ツ)_/¯ — Sammitch
– Sammitch, Commented May 25, 2021 at 21:03

El_Vanja · Accepted Answer · 2021-05-25 20:58:20Z

2

Utilizing array_map and arrow functions:

$result = array_map(fn ($genre) => $references[$genre], $return['movie_genre']);

Note that for versions prior to 7.4, when arrow functions were introduced, you'd have to write an anonymous function:

$result = array_map(function ($genre) use ($references) {
    return $references[$genre];
}, $return['movie_genre']);

You can easily substitute $return['movie_genre'] with your existing one liner.

answered May 25, 2021 at 20:58

El_Vanja

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1 Comment

Faye D. Over a year ago

Thanks a lot for your reply. Indeed it does what I asked for, so for that it deserves a thumb up, but for some reason I tend to like the other reply more, that's why I marked it as the accepted answer for my question!

AbraCadaver · Accepted Answer · 2021-05-26 23:24:16Z

1

Just flip the array of genres and compute the intersection of the keys. With your current code:

$return['movie_genre'] = array_intersect_key($references,
                             array_flip($return['movie_genre']));

Or combined:

$return['movie_genre']= array_intersect_key($references,
                            array_flip(array_map('trim', explode('/', $genre))));

If you really need those integer keys:

$return['movie_genre']= array_values(array_intersect_key($references,
                            array_flip(array_map('trim', explode('/', $genre)))));

Or to combine with your array_map to lookup the reference key from the value:

 $return['movie_genre'] = array_map(function($v) use($references) {
                                        return $references[trim($v)];
                                    }, explode('/', $genre));

And for fun with your current code; flip the reference array and grep for the genres and get the keys:

$return['movie_genre'] = array_keys(
                         preg_grep('/^'.implode('|', $return['movie_genre']).'$/',
                         array_flip($references)));

All that being said, I would probably do this:

foreach(array_map('trim', explode('/', $genre)) as $v) {
    $return['movie_genre'][] = $references[$v]; // or trim() here instead
}

edited May 26, 2021 at 23:24

answered May 25, 2021 at 20:49

AbraCadaver

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3 Comments

Faye D. Over a year ago

That was exactly what I was looking for, and didn't have the clear mind or inspiration to do it myself! Thanks a TON!

AbraCadaver Over a year ago

Out of curiosity, which one did you use?

Faye D. Over a year ago

I used this: array_values(array_intersect_key($genres, array_flip($return['movie_genre'])))

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